Optimization of Sample Preparation Methods to Improve the Efficiency of Nanoparticle Extraction from Environmental Samples

Abstract

A methodological gap in the study of environmental nanoparticles is largely due to their extremely low concentrations—typically around 0.01–0.1%—in ash, dust, or soil, which significantly complicates their extraction and quantification. This study demonstrates the efficiency of a novel sample preparation protocol for volcanic ash samples, involving sequential dispersion in 0.1 M NaCl and 2 mM Na₄P₂O₇, followed by nanoparticle extraction by flow field-flow fractionation in a rotating coiled column, using a 2 mM Na₄P₂O₇ solution as an eluent. Thise method ensures an increase in the mass of the extracted nanoparticles by one order of magnitude and enables the detection of elements such as Be, Cr, Co, Zn, Ag, Sb, Te, Ta, W, Tl, and Bi in ash-derived nanoparticles from various volcanoes in concentrations below the limits of detection by ICP–MS using deionized water as an eluent. In addition, the results of the procedure are not distorted by analytical artifacts, such as the formation of poorly soluble calcium phosphates during sample preparation. This approach provides a foundation for the systematic studies of ash-derived nanoparticles from a wide range of volcanic types, as well as of urban dust.